diff options
Diffstat (limited to 'kernel/smp.c')
| -rw-r--r-- | kernel/smp.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index d0ada39eb4d4..97f1d9765c94 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -329,6 +329,11 @@ EXPORT_SYMBOL(smp_call_function_single); * (ie: embedded in an object) and is responsible for synchronizing it * such that the IPIs performed on the @csd are strictly serialized. * + * If the function is called with one csd which has not yet been + * processed by previous call to smp_call_function_single_async(), the + * function will return immediately with -EBUSY showing that the csd + * object is still in progress. + * * NOTE: Be careful, there is unfortunately no current debugging facility to * validate the correctness of this serialization. */ @@ -338,14 +343,17 @@ int smp_call_function_single_async(int cpu, call_single_data_t *csd) preempt_disable(); - /* We could deadlock if we have to wait here with interrupts disabled! */ - if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK)) - csd_lock_wait(csd); + if (csd->flags & CSD_FLAG_LOCK) { + err = -EBUSY; + goto out; + } csd->flags = CSD_FLAG_LOCK; smp_wmb(); err = generic_exec_single(cpu, csd, csd->func, csd->info); + +out: preempt_enable(); return err; |